1. Field of the Invention
The present invention relates to testing equipment for non-utility power generators, etc., set up in high-rise buildings or other facilities in order to deal with such emergent situations as power breakdown, thereby determining whether or not they are in good condition.
Generally, power generators are broken down into high-voltage large-capacity and low-voltage small-capacity types. In the present disclosure, power generators having a voltage of 6.6 KV or 3.3 KV and a capacity of 800 KW or higher are called the high-voltage large-capacity type, while those having a voltage of 6.6 KV or 3.3 KV and a capacity of 500 KW or less are referred to as the high-voltage small-capacity type.
Similarly, power generators having a voltage of 415 v or 200 V and a capacity of 800 KW or more are called the low-voltage large-capacity type, while those having a voltage of 415 V or 200 v and a capacity of 500 KW or less are referred to as the low-voltage small-capacity type.
2. Prior Art
Referring now to FIG. 16, there is a typical power supply testing system used so far for non-utility power generators. As illustrated, a rectangular tank 71, through which a current passes, is charged with resistance water 72 of about 20.degree. C., While three pairs of vertically movable electrode plates 73 and 73 extending in three directions are immersed in the water 72, power is then supplied form a non-utility power generator (not shown) between the electrode plates 73 and 73 for the required time to test and confirm its performance such as its power generating ability or its serviceability.
Referring typically to the testing procedure of this type of testing equipment, there is constantly a current of about 642.6 A, when power is supplied from a non-utility power generator working at an output of 1,000 KVA, a power factor of 0.8 and a voltage of 415 V between the electrode plates 73 and 73 in the tank 71.
This power generator may be determined to have given power generating capability and serviceability, if there is no fault in its performance when power supply is continued for a given time in a matter of 3 hours.
However, the resistance water 72 in the tank 71 increases in temperature due to power supply and reaches as high as 80.degree. C., when it overflows a drainage port 75, as illustrated.
To what degree current are passed between the electrode plates 73 and 73 through the resistance water 72 is greatly affected by the temperature rise or fall of the resistance water 72 and the degree of contamination of the resistance water 72. This in turn leads to a variation in the preset testing conditions, say, an output of 1,000 KVA, a power factor of 0.8, a voltage of 415 V and a current of 642.6 A, under which the non-utility power generator works to supply power between the electrode plates 73 and 73 in the tank 71, thus resulting in a current exceeding 642.6 A flowing through the tank 71.
For that reason, there is often an overload on the generator and the associated engine.
Thus, the conventional testing equipment is designed to keep a current passing through it from exceeding the preset value of 642.6 A. For instance, this is achieved by moving the electrode plates 73 vertically to regulate the current-passing areas thereof in the resistance water 72 or supply an additional amount of fresh, low-temperature resistance water 72 through a water supply port 74, thereby limiting the temperature rise of the resistance water 72 in the tank 71 (because an increase in the water temperature gives rise of excess currents).
However, the conventional testing equipment mentioned above is of size so large that it is very inconvenient to carry to where the power generator testing is needed and too much time and labor are needed until it is set up.
No precise control of the electrode plates 73 is achieved as well, because much difficulty is involved in their vertical movement.
Another serious problem with this equipment is that it needs a continuous supply of fresh resistance water 72, which must immediately be discarded. Not only is the use of such a large quantity of water economically unfavorable, but the resistance water 72, once used, must be incontinently discarded as well, thus making working environmental worse.
In order to provide a solution to the above problems, we have already come up with a small, economical and safe testing system which can test a non-utility power generator regardless of where it is set up, prevent an unusual current increase during testing by simple operation and making good use of resistance water.
For this testing system--the first invention that underlies the present invention, we filed a number of patent applications including JP-A-62-204866, JP-A-1-202554, JP-A-2-82183, JP-A-2-89754, JP-A-2-89755, JP-A-2-249798, JP-A-2-86755, JP-A-3-76270 and JP-A-3-100180.
The prior testing system set forth in these publications will now be explained briefly with reference to FIG. 15.
The prior system, as illustrated, is built up of a tank 81 charged therein with a resistance liquid 86, a plurality of electrodes 82, each being fixed at one end on the upper portion of the tank 81, extending downwardly through the tank 81 and immersed in the resistance liquid 86 for receiving power form the non-utility power generator to be tested, a plurality of movable insulators 83, each being disposed through the electrode 82 variable, and a fan 85 for feeding air forcibly onto the surface of a radiator 84 which serves to cool the resistance liquid 86 in the tank 81 (and onto which water is jetted from a spray pipe).
This testing system enables load tests for non-utility power generators, etc., to be done with a simplified structure but with no need of using large amounts of water.
Later, we have invented another testing system incorporated therein with metallic resistance members.
This water-free or dry type of testing system--the second invention that we accomplished--is applicable to every generator from a high-voltage large-capacity type (with the voltage and capacity being at least 700 V and at least 800 KW, respectively), to a high-voltage small-capacity type (with the voltage and capacity being at least 700 V and at most 500 KW, respectively), to a low-voltage large-capacity type (with the voltage and capacity being at most 700 V and at least 800 KW, respectively) and to a low-voltage small-capacity type (with the voltage and capacity being up to 700 V and up to 500 KW, respectively). Note that these figures are given as tentative criteria. For these systems, see JP-A-4-21235 and JP-A-5-100180.
In some cases, non-utility power generators must be set up in intermountain remote districts--that are depopulated areas, where much difficulty is encountered in providing large-enough amounts of water.
In some cases, they must be tested even en snowy districts having a large snowfall, where considerable difficulty is again encountered in supplying a large quantity of water.
Here the reason we have the second invention will be explained briefly. Much difficulty has been involved in making a dry type of testing equipment for testing high-voltage large-capacitor generators of the order of 6.6 KV in voltage and 2,000 KW in capacity. This has been not only because loading devices serving as resistance elements--made up of a metal member are imperatively of large size and cost much, but also because it is difficult to provide any fine adjusting mechanism for setting load.
In addition, conventional dry type testing apparatus for testing low-voltage large-capacity (with a voltage of about 200 V and a capacity of about 2,000 KW), high-voltage large-capacity type (with a voltage of about 3.3 KV and a capacity of 2,000 KW), low-voltage small-capacity (with a voltage of about 415 V and a capacity of about 500 W) and high-voltage small capacity (with a voltage of 3.3 KV and a capacity of about 500 W) types of power generators must be separately fabricated, resulting in a considerable cost rise.
Thus, we have accomplished the second invention so as to provide a solution to the above problems.
However, we have found that the second invention again poses some problems.
One grave problem arises from a combination of a transformer and a low-voltage small-capacity type of capacity-variable loading element connected to the transformer so as to regulate the load (capacity and current) values in a stepwise manner--that is an important factor of the second invention. That combination, esp., the transformer, because of being very heavy, is very difficult to carry to intermountain remote districts--that are depopulated areas.
Another serious problem arises from the fact that control of the load values may be achieved only by use of a stepwise (usually four-stage) procedure. It is still preferable to make use of a water resistor capable of regulating load values by a stepless procedure, while relying up a movable insulator, so as to achieve fine control of the load values.
The present invention is concerned with an improvement in or relating to our prior inventions. More specifically, an object of the invention is to provide a change-over type of testing apparatus for non-utility power generators, etc., which can be reduced in terms of gross weight and production cost, enables every power generator to be easily, precisely and rapidly tested without cooperation with other test equipment, makes it possible to achieve fine control of capacity value, and enables the amount of resistance liquid used to be reduced to about 1/4 of that is needed for a testing apparatus made up of a water loading device alone.